1. Field of the Invention
The present invention relates to an ink jet printer and ink jet printing method. More particularly, the present invention relates to an ink jet printer and ink jet printing method in which ink can be dried quickly after printing operation.
2. Description Related to the Prior Art
An ink jet printer includes an ink jet head for printing, and is either of two types including a serial printer and a line printer. The serial printer includes a head carriage for moving the ink jet head in a sub scan direction that is widthwise to a recording sheet, and includes a mechanism for feeding the recording sheet in a main scan direction crosswise to the sub scan direction. In contrast, the line printer has a feeder for feeding the recording sheet one line after another. The line printer is advantageous in printing at a high speed.
In the line printer, ink is ejected through nozzles arranged in the range of the whole width of the recording sheet. An ejected amount of the ink per unit time is considerably high unlike the serial printer in which each belt-shaped region is recorded gradually from one side to the other. The highness of the ejected amount in the ink requires very long time for drying. The ink is likely to mix between wet droplets adjacent to one another, to cause occurrence of blur and drop of chroma. If the ink deposits on a feeder roller or the like, the ink is likely to contaminate the recording sheet. It is conceivable to dry the ink by use of a drier including a fan and a heater. However, disposition of the fan and the heater causes a problem of enlarging a size of the entirety of the line printer.
Note that, in the serial printer, the belt-shaped region can be enlarged with a greater range in a main scan direction. If the belt-shaped region has a considerably great range in the main scan direction, the ejected amount of the ink becomes very high to cause the same problem as the line printer. JP-A 8-174812 discloses a line printing type of ink jet printer in which a carriage or ink jet cartridge is provided with a heating ray emitter, which dries ink droplets or preheats recording material. However, there is no known technique for raising efficiency in the operation disclosed in this document to dry ink droplets or preheat recording material
In view of the foregoing problems, an object of the present invention is to provide an ink jet printer and ink jet printing method in which ink can be dried efficiently and quickly after printing operation.
In order to achieve the above and other objects and advantages of this invention, an ink jet printer comprises at least one ink jet head, including plural nozzles arranged in an array in a main scan direction, for ejecting a droplet of ink to recording material respectively at an ejected amount according to information of an image. A moving mechanism feeds one of the recording material and the ink jet head in a sub scan direction relative to a remaining one thereof, to print the image to the recording material two-dimensionally. At least one heater includes plural heater sections arranged in an array in the main scan direction, for applying heat to the recording material respectively in a heating region. A controller sets drying heat energy according to the ejected amount, and drives the heater to apply the drying heat energy to the heating region, to promote drying of the droplet in the heating region.
The heater is operated before, during or after operation of the ink jet head.
The controller sets the drying heat energy high according to highness in the ejected amount.
The moving mechanism feeds the recording material in the sub scan direction. Each of the heater sections in the heater corresponds to M nozzles included in the ink jet head, and Mxe2x89xa71.
The heater is disposed upstream from the ink jet head with reference to feeding of the recording material, and before the ink jet head operates, preheats the heating region where the droplet is ready to deposit.
In a preferred embodiment, the heater is disposed downstream from the ink jet head with reference to feeding of the recording material, and heats the droplet ejected by the ink jet head.
In another preferred embodiment, the heater heats the droplet simultaneously with ejection by the ink jet head.
The heater is disposed opposite to the ink jet head with reference to the recording material.
In a preferred embodiment, the heater is disposed close to the ink jet head with an inclination.
Furthermore, a speed signal generator generates a signal of a feeding speed at which the moving mechanism feeds the recording material. The controller sets the drying heat energy further in consideration of the feeding speed.
Furthermore, an information input unit inputs information of a recording material width of the recording material in the main scan direction. The controller designates heater sections to be driven among the heater sections in consideration of the recording material width.
The controller, if the ejected amount is equal to or lower than one reference amount, sets the drying heat energy as zero, and if the ejected amount is equal to or higher than the reference amount, sets the drying heat energy according to the ejected amount.
The heater comprises a thermal head, the plural heater sections are constituted by plural heating elements for pressurizing and heating the recording material.
Furthermore, a head shifter shifts the thermal head between a contact position and a non-contact position, wherein the thermal head, when in the contact position, contacts the recording material and is operated, and when in the non-contact position, is away from the recording material.
Furthermore, a protector belt is passed between the thermal head and the recording material, for protecting a surface of the thermal head pressurizing and heating the recording material.
The thermal head is disposed opposite to the ink jet head with reference to the recording material.
In a preferred embodiment, the heater is disposed beside the ink jet head, and directed to a recording surface where the droplet is ready to deposit.
In another preferred embodiment, the plural heater sections are constituted by plural infrared ray emitting elements for applying infrared rays to the heating region.
In another preferred embodiment, the moving mechanism is a head carriage for feeding the ink jet head in the sub scan direction to effect belt-shaped printing of the image. Furthermore, a moving mechanism moves one of the recording material and the head carriage relative to a remaining one thereof in the main scan direction by an amount of the belt-shaped printing, to record the image in a frame printing manner. The heater is secured to the head carriage beside the ink jet head.
The heater is disposed downstream from the ink jet head with reference to feeding of the head carriage, and before the ink jet head operates, preheats the heating region where the droplet is ready to deposit.
The ink jet head prints the image at a printing width of at least 80 mm in the main scan direction. The moving mechanism feeds the recording material at a feeding speed of at least 20 mm per second in the sub scan direction.
Furthermore, an information input unit inputs at least one of environmental temperature information, type information of the recording material, and thickness information of the recording material. The controller sets the drying heat energy further in consideration of at least one of the environmental temperature information, the type information and the thickness information.
According to another aspect of the invention, at least one ink jet head includes plural nozzles arranged in an array in a main scan direction, for ejecting a droplet of ink of an ultraviolet curable type to recording material respectively at an ejected amount according to information of an image. A moving mechanism feeds one of the recording material and the ink jet head in a sub scan direction relative to a remaining one thereof, to print the image to the recording material two-dimensionally. At least one ultraviolet ray emitter unit includes plural ray emitter sections arranged in an array in the main scan direction, for applying ultraviolet rays to the recording material respectively in a ray applying region. A controller sets ultraviolet ray intensity or ultraviolet ray amount according to the ejected amount, and drives the ultraviolet ray emitter unit according to the ultraviolet ray intensity or ultraviolet ray amount to cure the droplet in the ray applying region.